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From: Oliver Upton To: Marc Zyngier Cc: kvmarm@lists.linux.dev, Joey Gouly , Suzuki K Poulose , Zenghui Yu , Catalin Marinas , Will Deacon , Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v4 08/18] KVM: arm64: nv: Reinject traps that take effect in Host EL0 Message-ID: References: <20241025182354.3364124-1-oliver.upton@linux.dev> <20241025182354.3364124-9-oliver.upton@linux.dev> <87r083th7m.wl-maz@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87r083th7m.wl-maz@kernel.org> X-Migadu-Flow: FLOW_OUT Hey, On Sat, Oct 26, 2024 at 09:13:17AM +0100, Marc Zyngier wrote: > On Fri, 25 Oct 2024 19:23:43 +0100, > Oliver Upton wrote: > > > > Wire up the other end of traps that affect host EL0 by actually > > injecting them into the guest hypervisor. Skip over FGT entirely, as a > > cursory glance suggests no FGT is effective in host EL0. > > Yes, and this (thankfully) is by design! :-) > > > > > Note that kvm_inject_nested() is already equipped for handling > > exceptions while the VM is already in a host context. > > > > Signed-off-by: Oliver Upton > > --- > > arch/arm64/include/asm/kvm_emulate.h | 5 +++++ > > arch/arm64/kvm/emulate-nested.c | 29 ++++++++++++++++++++++++---- > > 2 files changed, 30 insertions(+), 4 deletions(-) > > > > diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h > > index a601a9305b10..bf0c48403f59 100644 > > --- a/arch/arm64/include/asm/kvm_emulate.h > > +++ b/arch/arm64/include/asm/kvm_emulate.h > > @@ -225,6 +225,11 @@ static inline bool is_hyp_ctxt(const struct kvm_vcpu *vcpu) > > return vcpu_has_nv(vcpu) && __is_hyp_ctxt(&vcpu->arch.ctxt); > > } > > > > +static inline bool vcpu_is_host_el0(const struct kvm_vcpu *vcpu) > > +{ > > + return is_hyp_ctxt(vcpu) && !vcpu_is_el2(vcpu); > > +} > > + > > /* > > * The layout of SPSR for an AArch32 state is different when observed from an > > * AArch64 SPSR_ELx or an AArch32 SPSR_*. This function generates the AArch32 > > diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c > > index e1a30d1bcd06..db3149379a4d 100644 > > --- a/arch/arm64/kvm/emulate-nested.c > > +++ b/arch/arm64/kvm/emulate-nested.c > > @@ -20,6 +20,9 @@ enum trap_behaviour { > > BEHAVE_FORWARD_READ = BIT(0), > > BEHAVE_FORWARD_WRITE = BIT(1), > > BEHAVE_FORWARD_RW = BEHAVE_FORWARD_READ | BEHAVE_FORWARD_WRITE, > > + > > + /* Traps that take effect in Host EL0, this is rare! */ > > + BEHAVE_IN_HOST_EL0 = BIT(2), > > nit: BEHAVE_IN_HOST_EL0 lacks an action verb (forward?). Thinking I'll squash this in (plus renaming in later patches): diff --git a/arch/arm64/kvm/emulate-nested.c b/arch/arm64/kvm/emulate-nested.c index db3149379a4d..b072098ee44e 100644 --- a/arch/arm64/kvm/emulate-nested.c +++ b/arch/arm64/kvm/emulate-nested.c @@ -22,7 +22,7 @@ enum trap_behaviour { BEHAVE_FORWARD_RW = BEHAVE_FORWARD_READ | BEHAVE_FORWARD_WRITE, /* Traps that take effect in Host EL0, this is rare! */ - BEHAVE_IN_HOST_EL0 = BIT(2), + BEHAVE_FORWARD_IN_HOST_EL0 = BIT(2), }; struct trap_bits { @@ -2279,7 +2279,7 @@ bool triage_sysreg_trap(struct kvm_vcpu *vcpu, int *sr_index) b = compute_trap_behaviour(vcpu, tc); - if (!(b & BEHAVE_IN_HOST_EL0) && vcpu_is_host_el0(vcpu)) + if (!(b & BEHAVE_FORWARD_IN_HOST_EL0) && vcpu_is_host_el0(vcpu)) goto local; if (((b & BEHAVE_FORWARD_READ) && is_read) || -- Thanks, Oliver